The Solubility System of Bi<SUB>2</SUB>(SO<SUB>4</SUB>)<SUB>3</SUB>-(NH<SUB>4</SUB>)<SUB>2</SUB>SO<SUB>4</SUB>-H<SUB>2</SUB>SO<SUB>4</SUB> and a Process Plan of Bismuth Recovery from Sulfide Ores
（1971）